An endoscope has been conventionally used, whose elongated insertion portion is inserted into a body cavity to observe the inside of the body cavity. In such an endoscope, an image pick up unit to obtain an observation image is arranged at a distal end of the insertion portion. A plurality of image pick up units which are of different types may be used to obtain an appropriate image meeting an observation purpose.
For example, in an endoscope disclosed in Jpn. Pat. Appln. KOKAI Publication No. 6-154155, first and second image pick up units having different angles of view are used.
In more detail, the endoscope disclosed in Jpn. Pat. Appln. KOKAI Publication No. 6-154155 includes an elongated insertion portion to be inserted into a body cavity, and an operating portion to be operated by an operator is arranged at a proximal end of the insertion portion. A universal cable extends from the operating portion, and a connector portion to connect the endoscope with an external device is arranged at an extending end of the universal cable.
First and second signal lines extends from the first and second image pick up units arranged at the distal end of the insertion portion, and the first and second signal lines are respectively inserted through the insertion portion, the operating portion, and the universal cable, and then connected with first and second connectors in the connector portion. The first and second connectors are respectively connected with first and second video processors to perform signal processing, through first and second scope cables.
The first and second video processors respectively output driving signals to the first and second image pick up units to drive the first and second image pick up units, process image signals input from the first and second image pick up units, and output the processed signals to a changeover switch portion.
The changeover switch portion selects one of the image signals from the first and second video processors, and outputs the selected signal to a monitor to selectively display one of images obtained by the first image pick up unit and the second image pick up unit on the monitor. For example, the image pick up unit with a narrow viewing angle is used to facilitate observation of an insertion target when inserting the endoscope, and the image pick up unit with a wide viewing angle is used to facilitate observation of a peripheral section when removing the endoscope.